In recent years, a cutting tool having a longer tool life than in the case of a conventional cutting tool has been required, along with an increasing demand for highly efficient cutting. Thus, in terms of the characteristics required for tool materials, improvements of wear resistance and fracture resistance, which are related to the life of a cutting tool, have been becoming increasingly important. In view of this, in order to improve such characteristics, a coated cutting tool is widely used which comprises, on a surface of a substrate comprised of a cemented carbide, cermet, cBN or the like, a coating layer consisting of one layer or two or more layers which is/are each comprised of a TiN layer, a TiAlN layer or the like.
Various techniques have been proposed in order to improve the above characteristics of a coating layer. For example, Patent Document 1 proposes a surface coated cutting tool comprising a titanium compound layer containing a first compound represented by chemical formula Ti1-xMxZy (wherein: X and Y respectively denote atomic ratios and satisfy 0<X≤0.3 and 0.1≤Y≤1; Z denotes an element of at least one kind selected from the group consisting of boron, oxygen, carbon and nitrogen; and M denotes Cr, Nb, Mo, Hf, Ta or W and does not include Al, Si and Zr) wherein: the first compound has a crystalline structure in which a ratio B/A of a peak intensity B for a (200) plane to a peak intensity A for a (111) plane in X-ray diffraction satisfies 0≤B/A≤1; and the crystal grain size is from 0.1 nm or more to 200 nm or less.